Space telegraphy.



L. DE FOREST.

SPACE TELEGRAPHY.

APPLIOATION FILED mm: 20, 1907.

Patented June 13, 1911.

2 BHEETSSHEET 1.

LEEDE FOREST, OF NEW YORK, N, Y., ASSIGNOB TO DE FOREST A CORPORATION OF NEW YORK.

run STATES PATENT FF E a RADIO TELEIHONE' 00.,

srAoE TELEGRAPHY.

To all whom it may concern: 1

Be it known that I, LEE DE FOREST, a citizen of the United States, and a resident of New York, in the county of New York and State of New York, have invented a new and useful Improvement in Space Telegraphy, of which the following is a specification.

My invention relates to systems for radiating electromagnetic waves for use in space telegraphy or telephony, and its object is to provide a system by means of which electromagnetic waves of great persistency, although not necessarily continuous, may be. radiated.

In the employment of the usual sonorous or oscillating circuit comprising a capacity and an inductance, together with a sparkgap for discharging-said capacity, there is a limit to which the persistence maybe in-.'

creased with a given frequency and a given amount of energy absorbed. It has been proposed therefore to employ continuouslyoscillating circuits commonly called singing-arc circuits, or circuits resembling the singing arc circuit and consisting of an inductance and a capacity connected in series with a spark-gap and supplied by a source of direct current through leads of large ohmic resistance. In a wireless telegraph system employing such continuously oscillating circuits to energize the transmitting antenna it is necessary, to. employ a device at the receiving station to commutate the currents developed in the receiving circuit if a variable-zero indicating device, such as a telephone receiver, is employed.

By means of the present invention I am able to obtain as great a persistency as is desirable while at the same time reducing the energy output required for the radiation of continuous electromagnetic waves and ob- -viating the necessity for commutating or interrupting the current in the receiving circuit.

It has been found that the adjustment of the arc electrodes which results in the production of oscillating currents when a singing arc circuit is energized by a source of direct current, is difficultto obtain and, when once obtained, is diificult to maintain, unless the arc of such circuit be surrounded by an atmosphere of hydrogen, as used at a very early date by P. E. M. Berthelotor by an atmosphere containing hydrogenas Specification of Letters Patent. Patented Application filed June 20, 1907.-

June is, 1911.

Serial No. 379,922.

employed long ago by Nikola Tesla. In

general, if a special atmosphere be not emenabled to dispense with the employment I of any special atmosphere surrounding the are by intermittently and automatically interrupting the arc, thereby pulling it through the critical distance of separation of the electrodes which determines the high frequency oscillatory or singing condition. Thus While it is difiicult to maintain the critical condition which determines oscillation in a singing arc circuit for even as long as thirty seconds without surrounding the arc with some special atmosphere, I find that by means of the present invention, I

can interrupt the arc, for example, by opening and closing the same, and thereby secure at each interruption the point at which the circuit begins to oscillate. The condition of oscillation will persist for at least one-tenth second during which time a practically' continuous train 'of oscillations having substantially uniform amplitude and comprising as many as fifty thousand oscillations will be developed,.the frequency of such oscillations being assumed in this case as being fivehundred thousand per second. Furthermore, by the present invention I am enabled to interrupt the prime source of energy, as by means of a key when the system herein described is employed for space telegraphy, and secure the instant production of oscillations, without redrawing or restriking the are upon the closure of said key, this being of great advantage in space telegraphy; V

My invention may best be understood by having reference to the drawings which accompany and form apart of this specification and which illustrate conventionally various forms of apparatus and circuit arrangements which have been found to be well adapted for the purpose of efl'ecting the'advantages set forth above.

In the drawings Figure 1 represents a singing-arc circuit constructed in accordance with the present invention and applied to a wireless telegraph transmitting system. Fig. 2 is a diagram similar to Fig. 1 and illustrating a modification. Fig. 3 represents a space telegraph transmitting system in which one of the arc electrodes of a singing arc circuit is moved with respect to the other. Fig. 4 shows a further modification in which a magnetic blow-out is employed for intermittently interrupting the arc.

In the figures, D is a source of direct current, A is a source of vibratory current, K is a key, R R are resistances, inductive or non-inductive, C is a condenser, L is an inductance, V is an antenna, and E is an earth connection. 1

In Fig. l, the vessel 1 is provided wit a thin diaphragm 9 to which is secured by the insulating bushings 10 the carbon anode -2. The solenoid 11, energized by vibratory trode periodically oscillated through the quency of currents from the generator A acts upon the magnetic core 12 which is secured to the diaphragm 9, and thereby creates relative movementbetween said anode 2 and liquid metalcathode 3. 3' represents a mass of. metal, mercury for example, supported in a supply tank which is connected with the vessel 1 by a .pipe having a valve 16.

In Fig. 2 relative'movement between the electrodes of the arcis created by the movement of the iron plunger 12' acted upon by the solenoid 11.

By employing the apparatus shown in Figs. 1 and 2, the amplitudes of the oscillations in thesinging arc circuit are periodically varied, or else interrupted, the are being pulled through the critical point a number of times per second, in the latter case.

In Fig. 3, 3 represents a metallic elecguide 19 by means of the cam 13, 13', which is driven by vany suitable motor 14. In this case, for example, the arc may be vstruck and drawn, say, sixty times er second, so that the receiving- 0 erator will hear a note in the receiving te ephone having a fresixty. Each time vthe arc is drawn, the critical condition during which the circuit oscillate's will be maintained for say one one-hundredth second, and during this time a very. large number'of practically continuous oscillations of substantially uni form amplitude willbe developed. I

In the system shown in Fig. 4:, the magnets 1d, 14 energized by the current of the battery B, which is serially connected with K 'which I have illustrate the coils 15 15 and the commutator I, serve scribed, and therefore I 0 not desire to be limited to the exact ap aratus and systems (i for the purpose of more fully disclosing my invention.

I claim: I 1. In a s stem for developing and radiating a practically continuous train of electromagnetic waves of substantially uniform amplitude, are electrodes, a source of current connected in circuit with the electrodes, capacity and inductance shunting the electrodes, and means for automatically moving the electrodes relatively to each other.

2. Ifi a system for developin and radiating a practically continuous tralnof electromagnetic waves of substantially uniform amplitude, are electrodes, a source of electric energy connected in circuit with the electrodes, capacity and inductance connected in shunt circuit to the electrodes, an means for automatically interrupting the arc between the electrodes.

3. Ina system for developing and radiating a practically continuous train of electromagnetic waves of substantially uniform amplitude, arc electrodes, a source of energy connected in circuit therewith, capacity and inductance connected in shunt circuit with the electrodes, means for establishing an are between said electrodes, andmeans for automatically interrupting the arc intermittently. w 4. In a system for developing and radiating a practically continuous train of electromagnetic waves. of substantially uniform v amplitude, are electrodes, a source of energy connected in circuit therewith, capacity and inductance connected in shunt circuit .with the electrodes, and means for automatically interrupting the are between the electrodes at a rate within the limit of audibility.

In testimony whereof, I have hereunto subscribed my name this 17 day of June 1907 LEE 15 FOREST.

Witnesses: 1

THOMAS I. GALLAGHER, A Roscon KENT. 

